In response to PA-13-080: Accelerating the Pace of Drug Abuse Research Using Existing Research Data, this competing renewal Trajectories of Nonmedical Prescription Drug Misuse builds on our parent R01 and proposes to use multiple cohorts of nationally representative longitudinal data to assess the individual patterns and trajectories of medical and nonmedical use of four classes of prescription medications (i.e., opioids, sedatives, stimulants, tranquilizers) from adolescence to adulthood and the development of substance use disorders (SUDs) and other long-term adverse consequences in adulthood. Despite increases in the medical and nonmedical use of prescription medications among adolescents and young adults in the U.S., relatively few prospective longitudinal studies have investigated the development of SUDs and other adverse consequences in adulthood. While there have been advances in understanding nonmedical use of prescription medications and short-term consequences, considerable gaps in knowledge remain due to limitations in measurement and study designs. Findings from our parent R01 suggest a great deal of heterogeneity in the nonmedical use of prescription medications during adolescence and young adulthood (ages 18-22). The Monitoring the Future (MTF) study provides a valuable opportunity to address new research questions that will lead to a more comprehensive understanding of medical and nonmedical use of prescription medications. We propose several secondary analyses using 39 nationally representative cohorts of approximately 585,000 high school seniors between 1976 and 2014 from the MTF study. The MTF longitudinal panel sample features 23 separate cohorts of approximately 55,200 high school seniors (modal age 18) who were followed 3-4 years (modal ages 21-22), 7-8 years (modal ages 25-26), and 17 years (modal age 35) later, resulting in four longitudinal waves of data for each cohort. The MTF study represents the only nationally representative longitudinal study that has sufficient measures and sample size to test for potential sex, racial, and socioeconomic status differences and to meet the objectives of our study, which aims to: 1) assess the individual patterns and trajectories of medical and nonmedical use of four prescription medication classes (i.e., opioids, sedatives, stimulants, tranquilizers) during the transition from adolescence (age 18) to adulthood (age 35) using cross-sectional and longitudinal panel data; 2) examine the associations between individual patterns and trajectories of medical and nonmedical use of four medication classes from adolescence to adulthood and development of SUDs and other adverse consequences (e.g., health problems, hospitalizations, and legal problems) during adulthood (age 35) using longitudinal panel data; and 3) investigate the risk and protective factors for individual patterns and trajectories of medical and nonmedical use of four prescription medication classes from adolescence to adulthood associated with development of SUDs and other consequences during adulthood (age 35) using a theory-based developmental model and longitudinal panel data.